An electrolytic cell of a size suitable for commercial processing involves a substantial current flow at the electrode within the cell in the presence to a vigorous chemical reaction. The materials used to fabricate the electrolytic cell are therefore degraded by two important factors mainly, a substantial current flow and extremely high chemical activity typically occurring at temperatures above ambient.
One such electrolytic cell is exemplified by a hydrogen peroxide cell. This involves a packed bed cathode within a suitable container, the cathode being formed of graphite chips. It is particularly important to obtain a coating on the chips which increases the efficiency of the packed bed cathode. The procedure of this disclosure sets forth a means of obtaining such a product, namely a graphite chip which has a composite layer on both sides which is substantially uniform in thickness. The layer is formed of particulate carbon and Teflon uniformly applied. At the time of processing, the slurry of carbon and Teflon (in particulate form) is applied to the individual chips, the chips being dried whereby a coating is formed on them. Moreover, this enables a chip which has an improved uniform coating able to handle the current flow required in the packed bed cathode. This is useful in prolonging the life of the cathode bed and to sustain relatively high performance for the cathode bed electrode. Further, this avoids chip degradation by enabling a more broadly distributed current flow, thereby eliminating current concentration at hot spots which degrade the chips comprising the trickle bed electrode.
While an individual chip may be degraded, even destroyed by the current flow concentration arising in the presence of the high chemical activity normal for an electrode bed, the loss of one chip is not immediately noticeable. However, the loss of chips is cumulative and degrades performance of the packed bed cathode, requiring more rapid replacement. Moreover, degradation of the bed may well also degrade the products obtained from the electrolytic process occurring in the electrolytic packed bed cell.
With the foregoing in view, the present disclosure is described as a method for the manufacture of a coated graphite chip suitable for use in a particulate chip cathode used in a packed bed electrolytic cell. The method of fabrication includes formation of a water slurry having graphite chips therein. A mix of particulate carbon and Teflon dispersion in the water is applied to the graphite chips which are subsequently dried in a rotary evaporator aided with vacuum removal, whereupon the chips are sintered for a specified time and temperature.